Vertical honing machine



March 31, 1964 K. D. MARKER ETAL 3,126,673

VERTICAL HONING MACHINE Filed Jan. 21, 1963 3 Sheets-Sheet 1 Wa g w w [A WW" I March 31, 1964 K. D. MARKER ETAL 3,126,673

VERTICAL HONING MACHINE Filed Jan. 21, 1963 3 Sheets-Sheet 2 mmflw/mwmmafiazg a, ham, 9 77M March 31, 1964 K. D. MARKER ETAL 3,126,673

VERTICAL HONING MACHINE Filed Jan. 21, 1963 3 Sheets-Sheet 3 6% W W/(W & W51

United States Patent M 3,126,673 VERTECAL HONENG MACHINE Kenneth D. Marker and Robert C. Muhl, Richmond, ind,

assignors to National Automatic Toni Company, Richmond, End, a corporation of ilndiana Fiied .l'an. 21, 13 63, Ser. No. 252,974 14 Claims. (Ql. Sit-34) This invention relates to a vertical honing machine having a relatively simple arrangement of dual feed for the expansion and contraction of the stones of the honing tool.

One object of the invention is to provide feed mechanism for expanding the bones continuously during the honing cycle for a work piece to compensate for the continual wear of the stones while the cycle is in progress.

Another object is to provide a precision type feed mechanism in the form of a feed cylinder and piston combination wherein the motive power is compressed air, a hydraulic check cylinder being associated therewith to adjustably regulate the rate of feed.

Still another object is to provide means for translating the reciprocating movement of the piston rod of the feed mechanism into rotary movement with respect to a threaded shaft which moves longitudinally for actuating the expansion rod for the stones of the honing tool.

A further object is to provide a stone expansion and contraction-compensation mechanism including a relatively light air motor which is operatively connected to the expansion rod for the stones to initially expand the stones into contact with the surface to be honed where upon the motor stalls thus providing an automatic initial adjustment of the stones diametrically to the work.

Still a further object is to provide means for translating the rotary motion of the air motor into longitudinal movement of the stone expansion rod by rotating the threaded shaft relative to a sleeve that is threaded thereon, a gear being threaded on the sleeve and rotated by the feed mechanism.

An additional object is to provide a timing arrangement for the air motor wherein a first timer actuated at the beginning of the honing cycle sends air to the air motor for a period of time slightly longer than required for the stones to contact the work surface, and to provide a second timer actuated at the completion of the cycle for sending air to the motor to reverse its direction of rotation for contracting the stones, the second timer being set for a shorter period of time than the first one so that the differential setting between the timers compensates for stone wear from work piece to work piece, starting the hones at the same diameter for succeeding work pieces as they were initially for the first work piece. Feed-out and compensation are critical factors in a honing machine and our air motor and timing arrangement adequately meet the requirements.

Another additional object is to provide a novel operative connection between a shaft driven by the feed cylinder and a shaft driven by the air motor to drive the threaded shaft longitudinally which in turn actuates the stone expanding rod, a sleeve on the threaded rod being threaded in a gear that is geared to the feed cylinder shaft, the shaft of the air motor being geared to rotate the threaded shaft.

3,126,673 Patented Mar. 31, 1964 Still another additional object is to incorporate the feed cylinder and the air motor in a honing machine wherein a reciprocating mechanism reciprocates the honing tool through the work piece and means is provided for simultaneously rotating the tool, a crank being provided to effeet the reciprocating motion of the reciprocating mechanism and the entire assembly being carried by a vertically movable head of the honing machine which is adaptable to assume a lower working position or an upper load position.

A further additional object is to provide an automatic operating cycle for the components above enumerated which may be initiated by pressing a start button and automatically terminates after a cycle of operation comprising downward movement of the head to work position, rotation of the hone, movement of the feed mechanism in the feeding direction, actuation of the air motor for advancing the stones to the work, reciprocation of the tool with respect to the work until the bore being honed is sized whereupon an automatic gauge enters the work and causes the feed mechanism to retract, the air motor to reverse for contracting the stones, movement of the head upwardly to load position and stoppage of the drive motor at the top of the stroke of the reciprocating mechanism.

With these and other objects in view, our invention consists in the construction, arrangement and combination of the various parts of our honing machine, whereby the objects above contemplated are attained, as hereinafter more fully set forth, pointed out in our claims and illustrated in detail on the accompanying drawings, wherein:

FIG. 1 is a front elevation of a vertical honing machine embodying our invention;

FIG. 2 is a vertical sectional view substantially on the line 2-2 of FIG. 1;

FIG. 3 is an enlarged vertical sectional view on the line 3-3 of FIG. 2 showing a feed actuating mechanism;

FIG. 4 is an isometric view of the operating components of our vertical honing machine;

FIG. 5 is an operational diagram of such components, and

FIG. 6 is a semi-diagrammatic view of a hydraulic check feed control forming part of such operating components.

On the accompanying drawings we have used the reference numeral 1 to indicate a drive motor for rotating a drive shaft 7 as shown diagrammatically in FIG. 4. The drive shaft 7 is journaled in a head 50 and is driven by a belt 2 and an upper drive shaft 5. The shaft 5 has a spline 6 for operative connection to the drive shaft 7. An electro-rnagnetic brake 3 is illustrated for the shaft 5, the brake being applied when the electro-magnetic coil thereof is deenergized.

Referring to FIG. 2 the drive shaft 7 is shown journaled in the head 5d, and the head in turn is supported for vertical sliding movement on guide rods which are stationarily mounted on a vertical column 66 of the honing machine in the general manner shown in the Swanson Patent No. 3,025,642 and the Bargren Patent No. 3,032,932. The shaft 5 and the brake 3 are also illustrated but the motor 1 and belt 2 are omitted. The motor may be electric, hydraulic or pneumatic as desired.

The head 5% is adapted to assume a lower working position or an upper load position accomplished by pneumatic operation of a head cylinder 49 from which a piston rod 51 extends. The piston rod is adjustably mounted by means of lock nuts in a column bracket 52 of the column 66, and the head is provided with dogs 54 and 56 adjustably mounted on the head 56} and adapted to operate limit switches 53 and 55 when the head is down in the working position or when it is up in the load position respectively. The switches 53 and 55 limit the movement of the head in the usual manner which forms no part of our present invention. A head safety latch is provided in the form of a plunger 57 normally held disengaged from a rack 53 when a cylinder 59 for the plunger is subjected to pneumatic pressure during operation of the machine. Thus upon failure of pressure the plunger is extended to contact the rack and prevent detrimental settling of the head 50 as shown in the co-pending application of Calvert et al. Serial No. 102,797, filed April 13, 1961.

The shaft 7 has a change gear 8 thereon meshing with a change gear It) of a sleeve 11. The sleeve 11 through a splined connection drives a spindle 12 to which a honing tool 38 may be screwed having the usual stones 37 and expansion rod 36 for adjusting them as shown diagrammatically in FIG. 4. As shown in FIG. 2 the sleeve 11 is journaled in the head 50, the spindle i2 telescopes inside the sleeve and the upper end of the spindle is provided with a pair of thrust bearings 67 which are secured in the lower end of a reciprocating mechanism 19. The mechanism 19 is in the form of a housing that is vertically slidable on guide rods 68 and 69 and is shown diagrammatically box-like in FIG. 4.

For reciprocating the spindle 12 through its operating stroke, the mechanism 19 is vertically rcciprocated by means of a lever 18 pivoted to a bracket 70 secured within the head 50 and operatively connected to the mechanism by a link 71. A worm gear 16 is provided with a crank pin 72, the throw of which may be adjusted relative to the axis of rotation of the Worm gear by an adjusting screw 20. A link 17 operatively connects the crank pin 72 to the lever 18 whereby rotation of the Worm gear 16 oscillates the lever 18 about its pivot to the bracket 70, thus vertically reciprocating the mechanism 19 with the degree of vertical reciprocation being adjustable. Thereby the stroke of the tool 38 and the homes 37 relative to the cylinder or bore being honed may be adjusted. For rotating the worm gear 16 a worm I is provided which through a shaft 73 is rotated by bevel gears 14. The bevel gears are rotated by a shaft 74 shown diagrammatically in FIG. 4. The shaft 74 has a change gear 13 thereon meshing with a change gear 9 on the drive shaft 7.

For feeding the stones 37 radially relative to the tool 38, a cone 84 on the lower end of the expansion rod 36 is provided in the usual manner as shown for instance in Calvert Patents Nos. 2,820,329 and 2,845,752, so that by upward movement of the expansion rod the stones contract and by downward movement they expand. The expansion rod 36 has a bayonet connection with a rod 35 which extends slidably upward through the spindle '12 and is connected by a thrust bearing 34 to a threaded shaft 33. The shaft 33 threads at 43 through a sleeve 32, the external surface of which is also threaded (but left-hand relative to the right-hand threads 43) in a gear 31. The gear 31 is driven by a gear secured to a vertical shaft 75 which has a sliding spline 29 for operative connection with miter gears 28 driven by a shaft 75. The shaft 75 has a pinion 27 thereon meshing with a rack 22 of a piston rod 77 entering a feed cylinder 21 which is pneumatically operated.

A bracket 23 is mounted on the piston rod 77 and is connected by a rod 24 to a hydraulic check cylinder 25, the rod having a piston 79 thereon within the cylinder as shown in FIG. 6. The check cylinder 25 is of the type that permits oil to slowly flow from one side of the piston 79 to the other through a needle valve 78 provided with a regulator knob 26 as shown diagrammatically and the piston is of the type that permits fast flow of oil through a return valve 32. To function properly, the needle valve 78 should be pressure-compensated in the usual manner. Accordingly the piston can descend only slowly but may ascend quickly under the forces exerted on it by compressed air acting in the feed cylinder 21. The usual balance or oil makeup cylinder is shown at 80 in FIG. 4. The bracket 23 is adapted to trip a limit switch 39 for a purpose which will hereinafter appear.

An air motor 40 is provided for rotating, by means of a belt 81, a shaft 41. The shaft 41, through miter gears 42, rotates the threaded shaft 33 clockwise and since it is threaded in the sleeve 32 it pushes the rod 35 downwardly (when the motor 4-0 rotates forwardly) through a thrust bearing 34, thereby moving the expansion rod 3-6 downwardly to expand the stones 37 to contact the bore of the work being honed. The air motor 40 is a relatively light motor and may be supplied with low pressure air through a suitable pressure regulator, the pressure being regulated to suit the stones and work being honed so that the motor stalls when the stones contact the work and exert the desired honing pressure. The air motor 46 is reversible, and acts in a compensation phase as will hereinafter appear when reversed, at which time it threads the shaft 33 upwardly through the sleeve 32 for retracting the stones 37 from the surface being honed.

It is desirable to have indication when the stones 37 are worn out and when the push rod 36 is fully contracted so the tool will accept new stones. This is accomplished by a limit switch 47 shown in FIG. 4 actuated by screws 46 and 48 of a bracket 44. The bracket 44 is threaded on the shaft 41 and is adjustable relative thereto by means of an adjusting knob 45 for set up purposes. When the stones are expanded the knob 45 is further to the left than illustrated in FIG. 4 and the screw 48 trips the switch 47 to energize a suitable pilot light 85. The knob 45 moves to the left as the stones are contracted until screw 46 trips the switch 47 to energize another pilot light 86.

From the foregoing description of the parts and their operation it will be noted that the feed cycle accomplished by the air cylinder 21 and the initial advance-compensation cycles accomplished by the motor 40 are independent of each other but operate concurrently.

Adjacent the reciprocating mechanism 19 is a switch 62 adapted to be actuated by a vane when the vane enters a slot of the switch. The vane is variably positioned on the reciprocating mechanism by adjusting screws 61. The purpose of the vane switch is to stop the reciprocating stroke of the spindle in the full-up position.

In connection with the tool 38, a torque rod 63 is provided for actuating a limit switch 64 for a purpose which will hereinafter appear. The tool also has a gauge ring 87 adapted to enter the bore of the work when it has been honed to size in the manner disclosed in the Calvert patents last above mentioned. The torque rod 63 actuates the limit switch 64 only after such entry.

By way of general comments, the change gears 53 and 16 determine the rpm. of the spindle 12 with relation to the drive shaft 7. These gears may be changed to slow down the rotation of the tool 38 when a larger tool is used or for securing any desired rate of rotation for other considerations. The change gears 9 and 13 determine the s.p.rn. (strokes) of the reciprocating mechanism 19, and may be changed for speeding it up or slowing it down to suit the work being honed.

The unit shown at the left at FIG. 4 including the feed cylinder 21, the hydraulic check cylinder 25 and associated parts provide for continuously feeding the stone against the work during a honing cycle which may involve several vertical reciprocations of the bones 37 relative to the bore being honed. The feed mechanism operates independent of reciprocation of the mechanism 19, independent of compensation for stone wear resulting from operation of the motor 49 and independent of the spindle 12. The piston rod 77 and the rod 24 of the air cylinder 21 start to move downwardly when the honing cycle starts and they quickly retract when the work sizes out. The feed mechanism is powered by compressed air supplied to the cylinder 21 and its feed rate is controlled by the regulator valve 73 and its regulator knob 26.

The stone expansion and contraction-compensation mechanism, beginning with the motor 40 and ending with the threaded shaft 33, effects a rapid advance of the stones to the work face during initial expansion and rapidly contracts the stones at the end of a honing cycle a predetermined amount to compensate for stone wear. The motor 40 is controlled by two adjustable timers T1 and T2 shown in the operational diagram FIG. 5. A cycle start button 88 is shown and the vane switch 62 and limit switch 64 are also illustrated. A suitable electric circuit is provided to accomplish the desired cycling of the head cylinder 49, feed cylinder 21 and motor 49 which are also shown diagrammatically. The timers T1 and T2 may be time delay relays which are adjustable in setting as indicated by pointers and circumferentially spaced radial marks thereadjacent. Without going into the electrical circuits and relay arrangements, FIG. 5 indicates the sequence of operation (A) and (B) with connecting arrows for starting the honing cycle, and (C), (D), (E) and (F) with dotted connecting arrows for ending the honing cycle.

When the start button 88 is depressed, operation (A) takes place which consists of supplying air pressure to the down (D) port of the head cylinder 49 to cause the cylinder and thereby the head 59 to move downwardly relative to the stationary piston rod 51. The head moves from an upper load position to lower work position. Thereupon the limit switch 53 (FIG. 4) interlocks for performing operation (B) which consists of energizing the drive motor 1, operating the timer T1, energizing the brake 3 to release it, and introducing compressed air to the down (D) port of the feed cylinder 21. The timer T1 sends air to the forward (F) port of the motor 40 for expanding the stones 3'7 (through the belt 81, shaft 41, miter gears 42, threaded shaft 33, thrust bearings 34, rod 35 and expanding rod 36). The timer T1 may be set for instance at 1.0 second when the actual time for the hones to engage the work surface is 0.8 second. These settings are indicated by means of legends in FIG. 5.

When the stones advance into contact with the work, the motor 40 stalls and the timer T1 times out. At this time the honing operation is in progress, the reciprocating mechanism 19 stroking the bones vertically in the work and the feed mechanism 212S slowly expanding the hones at approximately the rate that they wear away. At each down stroke of the tool 58, the gauge ring 87 attempts to enter the bore of the work.

Finally when the work is honed to size, the gauge ring 87 enters the bore so that the torque arm 63 depresses the micro switch 64 to effect operation (C) which is an interlock that effects retraction or upward movement of the rod 77 of the feed cylinder 21 by sending air to the up (U) port thereof. The electric circuit, relays and control valves for this operation as well as the down operation of the feed cylinder 21 is, of course, designed to exhaust from the down port when the up port receives air and vice versa. Circuitry of this kind is standard equipment in the machine tool art and need not be gone into in detail.

When the piston rod 77 moves upwardly, the bracket 23 actuates the switch 39 shown in FIG. 4 which causes an interlock that starts the next operation (D), the result of which is to send air under pressure to the up port of the head cylinder 49, operate the timer T2 to send air to the reverse port (R) of the motor 40 and cause operation (E) as a result of the head 50 traversing up to load position and actuating the limit switch 55. With the timer T2 (set at 0.8 second) times out, the motor 40 is stopped with the stones 37 assuming a position at the same diameter as when they started into the first piece of work. The stones are therefore ready for the second piece of same dimensions which the operator positions in the machine after removing the first piece. Thus the motor 40, and the timers T1 and T2 set at different times as described, exactly compensate for the wear that has occurred on the stones 37 during the honing of the first piece of work. If it is found that there has been undercompensation, the setting of the timer T2 may be increased to avoid loss of cycle time. In that case the stones would be at a greater diameter than the initial diameter because of having lost more material than was anticipated so that the timer T2 allowed them to contract too far. Initial advance on the next cycle will probably not carry the face of the stone to the work surface due to the timer T1 timing out first. In such case, the feed mechanism 21-25 must complete the advance at a loss of cycle time. The condition will become worse on succeeding cycles since the feed mechanism will reverse the same amount if fed forward (including the distance it traveled to complete the initial advance). This plus the already too long a contract time will continue to set the stone face farther from the work each time.

On the other hand, if it is found that there has been overcompensation, the result will be poor stone life. In that event, the setting of the timer T2 is decreased. If there is overcompensation, when the stone is ready for the second cycle it will be at too small a diameter because the timer T2 did not allow enough time to contract to the original set-up clearance. If this condition is drastic enough the stone will shear on the work piece bore, but if not too bad the stone may only shear on low limit parts. A low limit part, however, will shear the stone on entry. The condition will not become worse due to the combination action of the feed mechanism and the compensating mechanism because the stone cannot advance any farther than the work surface will allow because of the motor 4-9 stalling, and the feed mechanism will return the same amount it fed outwardly for succeeding work pieces.

From the foregoing specification it will be obvious that we have provided (1) A combination of pneumatic feed for expanding the hones controlled by a hydraulic check cylinder to compensate for stone wear during the honing cycle on a piece of work,

(2) Rapid advance for initial expansion at the beginning of a honing cycle with stalling of the motor that effects the advance upon contact of the stones with the work surface, and

(3) A rapid contracting action of the stones at the completion of the cycle, the expansion and contraction being controlled by timers in such manner as to compensate for stone wear from piece to piece.

Some changes may be made in the construction and arrangement of the parts of our honing machine without departing from the real spirit and purpose of our invention, and it is our intention to cover by our claims any modified forms of structure or use of mechanical equivalents which may reasonably be included within their scope.

We claim as our invention:

1. In a honing machine of the character disclosed, a spindle for rotating a honing tool and a rod slidable therethrough for effecting expansion and contraction of the stones of the tool, means for rotating and reciprocating said spindle, and means for moving said rod longitudinally of said spindle, said last means comprising a threaded shaft operatively connected to said rod, a sleeve threaded on said shaft, a gear threaded on said sleeve and a pair of means to rotate said rotatable shaft and said gear, one of said pair of means comprising feed mechanism to compensate for wear during a honing cycle and the other of said pair of means comprising a stone expansion and contraction-compensation mechanism to compensate for wear from work piece to work piece, said feed mechanism being pneumatically powered and including a hydraulic 43 check means to determine the rate of feed, and said stone expansion and contraction-compensation mechanism comprising an air motor which stalls upon contact of the stones with the surface to be honed.

2. A honing machine according to claim 1 wherein a pair of timers are provided for operating said air motor, one of said timers being operable to effect operation of said air motor in the stone expansion direction and the other of said timers being operable to effect operation of said air motor in the stone contraction direction.

3. A honing machine according to claim 2 wherein said first timer times out after the stones engage the surface to be honed and the other times out in a shorter period to render the effective diameter of the stones substantially the same after being worn by honing a work piece as at the beginning of the honing operation thereon.

4. A honing machine according to claim 2 having a cycle start control for effecting operation of said first timer, and gauge means for the work operable to effect operation of said second timer when said gauge means enters the work.

5. In a honing machine of the character disclosed, a head movable to upper load and lower work positions, a spindle carried in said head for rotating a honing tool and a rod slidable therethrough for effecting expansion and contraction of the stones of the tool, means for rotating and reciprocating said spindle relative to said head, and means for moving said rod longitudinally of said spindle, said last means comprising a threaded shaft operatively connected to said rod, a sleeve threaded on said shaft, a gear threaded on said sleeve and a pair of means to rotate said rotatable shaft and said gear, one of said pair of means comprising feed mechanism supported by said head to compensate for wear during a honing cycle and the other of said pair of means comprising a stone expansion and contraction-compensation mechanism supported by said head to compensate for wear from work piece to work piece, said feed mechanism being pneumatically powered and including a hydraulic check means to determine the rate of feed, said stone expansion and contr action-compensation mechanism comprising an air motor which stalls upon contact of the stones with the surface to be honed.

6. A honing machine according to claim 5 wherein a pair of timers are provided for operating said air motor, one of said timers being operable to effect operation of said air motor in the stone expansion direction and the other of said timers being operable to effect operation of said air motor in the stone contraction direction, a cycle start control for moving said head downwardly, and gauge means for the work operable to move said head upwardly when said gauge means enters the work.

7. A honing machine according to claim 6 wherein said first timer times out after the stones engage the surface to be honed and the other times out in a shorter period to render the effective diameter of the stones substantially the same after being worn by honing a work piece as at the beginning of the honing operation thereon.

8. A honing machine according to claim 6 wherein said cycle start control also effects operation of said first timer and said gauge means effects operation of said second timer when said gauge means enters the work.

9. In a honing machine of the character disclosed, a head, a spindle carried by said head for rotating a honing tool and a rod slidable therethrough for effecting expansion and contraction of the stones of the tool, means for rotating and reciprocating said spindle relative to said head, and means for moving said rod longitudinally of said spindle, said last means comprising a threaded shaft operatively connected to said rod, a sleeve threaded on said shaft, a gear threaded on said sleeve and a pair of means to rotate said rotatable shaft and said gear, one of said pair of means comprising feed mechanism supported by said head to compensate for wear during a honin cycle and the other of said pair of means comprising a stone expansion and contraction-compensation mechanism to compensate for wear from work piece to Work piece, said feed mechanism being pneumatically powered and including a hydraulic check means to determine the rate of feed, said stone expansion and contraction-compensation mechanism comprising an air motor which stalls upon contact of the stones with the surface to be honed, a cycle-start control for moving said head downwardly, and gauge means for the work operable to effect movement of said head upwardly when said gauge means enters the work.

10. A honing machine according to claim 9 wherein a pair of timers are provided for operating an air motor, one of said timers being operable to effect operation of said air motor in the stone expansion direction and the other of said timers being operable to effect operation of said air motor in the stone contraction direction, said cycle-start control effecting operation of said first timer and said gauge means effecting operation of said second timer.

11. A honing machine according to claim 10 wherein said first timer times out after the stones engage the surface to be honed and the other times out in a shorter period to render the effective diameter of the stones substantially the same after being worn by honing a Work piece as at the beginning of the honing operation thereon.

12. In a honing machine, the combination comprising a tubular spindle mounted for reciprocation and rotation, means connected to said spindle for reciprocating and rotating the same, a push rod slidably mounted within said spindle and adapted to coact with a push rod in a honing tool to expand honing elements carried by the tool into engagement with a work piece bore to be honed, movable means acting on said first named push rod to move the latter in the direction of honing element expansion, said movable means including a motor capable of stalling when it has advanced the honing elements into contact with the work piece bore, thereby to exert pressure by the push rods on the honing elements in proportion to the stalling pressure of said motor and to compensate for variations in initial tolerance of the bore to be honed, and hydraulically checked pneumatic means to thereafter regulate the pressure exerted by the push rods on the honing elements to regulate the rate of honing element feed.

13. A honing machine comprising a tubular spindle mounted for reciprocation and rotation, means connected to said spindle for reciprocating and rotating the same, a push rod slidably mounted within said spindle and adapted to coact with a push rod in a honing tool to expand honing elements carried by the tool into engagement with a work piece bore to be honed, movable means acting on said first named push rod to move the latter in the direction of honing element expansion, said movable means including an air motor capable of stalling when it has advanced the honing elements into contact with the work piece bore, thereby to exert pressure by the push rods on the honing elements in proportion to the stalling pressure of said air motor and to compensate for variations in initial tolerance of the bore to be honed, and hydraulically checked pneumatic feed means to thereafter regulate the pressure exerted by the push rods and the honing elements to regulate the rate of honing element feed, said feed means compensating for honing element wear during the honing cycle.

14. In a honing machine, the combination comprising a tubular spindle mounted for reciprocation and rotation, means connected to said spindle for reciprocating and rotating the same, a main push rod slidably mounted within said spindle and adapted to coact with a push rod of a honing tool to expand honing elements carried by the tool into engagement with a work piece bore to be honed, a movable shaft acting on said main push rod to move it in the direction of honing element expansion, a tubular guide means into which said shaft projects for axial and rotational movement therein, said guide means being axially movable with said spindle, a threaded sleeve axially movable within and restrained against rotation relative to said tubular guide and into which said shaft is threaded and axially movable relative to said guide means and said spindle, an air motor for rotating said shaft, said air 5 l d piece honing cycle for compensating for hone element Wear by continuously resetting said sleeve in said nut and thereby said shaft in the honing element expansion direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,251,607 Astrowski et al. Aug. 5, 1941 2,819,566 Johnson Jan. 14, 1958 3,097,453 Swanson July 16, 1963 

1. IN A HONING MACHINE OF THE CHARACTER DISCLOSED, A SPINDLE FOR ROTATING A HONING TOOL AND A ROD SLIDABLE THERETHROUGH FOR EFFECTING EXPANSION AND CONTRACTION OF THE STONES OF THE TOOL, MEANS FOR ROTATING AND RECIPROCATING SAID SPINDLE, AND MEANS FOR MOVING SAID ROD LONGITUDINALLY OF SAID SPINDLE, SAID LAST MEANS COMPRISING A THREADED SHAFT OPERATIVELY CONNECTED TO SAID ROD, A SLEEVE THREADED ON SAID SHAFT, A GEAR THREADED ON SAID SLEEVE AND A PAIR OF MEANS TO ROTATE SAID ROTATABLE SHAFT AND SAID GEAR, ONE OF SAID PAIR OF MEANS COMPRISING FEED MECHANISM TO COMPENSATE FOR WEAR DURING A HONING CYCLE AND THE OTHER OF SAID PAIR OF MEANS COMPRISING A STONE EXPANSION AND 